Means for correcting printing plates



Dec, 16? W24 1,519,775

7 E. ERHCKSSON MEANS FOR CORRECTING PRINTING PLATES File d Nov. 8, 1923 lurk n T07 .1: mil EIZC 0350M Patented "nee. is. neat.

\ warn EEICSON, CHICAGU, ILLIN'UIS, ASSIGNOR T W. A. HELD COMPANY,

0F CHICAGO, ILLINOIS, A CQRP ORATION 01E ILLINOIS.

150B CQRRECTING PRINTING lPllATEg.

Illinois, have invented certain new and use ful Improvements in Means for Gorrecting Printing Plates, of which the following is a specification.

In preparing printing plates for the press,

N it is. necessary to true up or level the printing surface by the application of pressure to a degree necessary to transfer any variations in level from the type surface to the back of the plate, which latter may be afterto wards shaved or otherwise treated to remove such inequalities due to variations in thickness and other causes.

In modern practice, it is customary to true up the printing plates in specially prepared presses, and the present invention relates to a backing for the plates to be corrected, and so constructed as to yield locally to the degree required to impart the pressures necessary to bring the printing surface of the plate to a true plane or other intended configuration. It will be under stood from the above that the invention has application to the correction of'curved plates for cylindrical presses as well as those intended for use on flat presses.

In performing the service indicated, it has usually been the practice to provide backing sheets of paper or composition rovide with an embossed surface adapte to belocally crushed down in the correction process, which practice used up the sheet and rendered it unfit for further use, but the present invention. is directed to a permanent backing intended to constitute an integral portion of the press as a wholeand so constructed as to be capable of continuous use throughout along period of time.

In the drawings: y Figure 1 is a sectional elevation showing the upper and lower plates of a press wit the correction members of the present invention bearing against a printing plate in its uncorrected state Fig. 2 is a similar view showing the rela tion of'the same parts after corrections;

ing process.

Application filed Nbvember 8, 1923. Serial 1%. 673,473.

Fig. 3 is a perspective detail largely in sec. tion showing the correction members of the present invention; and

Fig. 4' is a sectional detail showing a modified form of the same.

The upper plate of the correction press 10 is provided with apertures 11 through which are extended gas burners 12 for heating the press plate to the degree required to render pliable the printing plate 13 which is being corrected. The printing plate is provided with a type surface 14 which, it' will be noted from inspection of Fig. 1, is more or less irregular prior to the correct- The upper press plate cooperates with a lower press plate 15 upon which is mounted a relatively thick backing layer 16 of rubberor other yielding material. Above the rubber backing is located a metal face plate 79 17 provided with a large number of apertures 18, each .of which receives a pin 19 provided on its lower end with a head 20 which bears against, the rubber backing. llhe pins are of a length to brin their upper or contact ends normally slight y above the surface of, the face plate 17 and'into contact with the back -surface of the printing plate under correction.

In'F-ig. 4 is shown a slight modificationso in lieu of a rubber backing, a metal plate 21 is employed provided with erforations 22 adapted to receive and gui e the lower ends 23 of pins 24 provided with flanges 25,

which latter furnish heads for the contact of coil springs 26 which serve to hold the pins in elevated position. In this construction the face late 17 is held in spaced relation to the acking plate 21 by means of tie rods 27 and spacers 28, the tie rods also 00" 7 serving to bolt the correction elements to of the plate to the back thereof, as in Fig. 2. During this operation, the pins will be depressed in varying degree against the yielding surface of the rubber backing, so that inequalities and imperfections in the printing surface will be eliminated. By providing a plurality of pins furnishingcom tact points adapted to yield locally to the requiredau'iount, every portion of the printing plate will have the required pressure imparted thereto to insure the necessary correction.

The correction elements of Fig. 4 are employed in the same manner as that above described, but in this case, the individual springs subserve the same function as the rubber backing sheet and locally yield to the required amount in each instance to secure the necessary correction.

By employing spaced contact pins in conjunction with arubber backing, displacement areas are provided between the heads of the pins for permitting a displacement or bulging up of the rubber to the degree required to compensate for the depression of the rubber at points in contact with the pm heads. This renders the arrangement far superior to one in which a rubber sheet is alone employed for contact with the plate being corrected for the reason that without the pins,

. the rubber, in unbroken contact with the printing plate and subjected to a varying pressure due to inequality in the plate surface, will have difliculty in accommodating itself locally to the distortional influence v of the pressure applied, so that excessive pressures may be required, which may tend to distort or impair the type surface or render the application of an excessively high temperature necessary in order to effect correction. By providing a multiplicity of point contacts, the displacement areas are subdivided, so that small areas of the rubber between the pin heads can readily distort to locally accommodate all variations in pressure which may be encountered. -At the same time the interposed pins serve to protect the rubber rom the deleterious effects of the heat applied to the printing plate, and permit the use of such temperatures as may be best fitted to render the plate pliable Without directly imparting such heat to the rubber. I

For the reasons outlined, the use of the present invention permits of a much greater variation in heat and pressure than might otherwise be practically employed and permits the correction elements tobe continuously used without material wear or impairment.

I claim:

1. In devices for correcting printing plates, the combination of a yieldable'backing, a rigid face plate, and yieldable contact members carried by the face plate and bear- 4. In devices for correcting printing plates, the combination of a rigid faceplate, a plurality of closely spaced correction elements slidably .mounted through the face plate and normally projecting above the face plate, and yieldable backing means for the contact elements, substantially as described.

5. In devices for correcting printing plates, the combination of a rigid face plate provided with a plurality of apertures, pins inserted through the apertures and normally projecting above the face plate, and yieldable backing means for said pins, substantially as described.

6. In devices for correcting printing plates, the combination of a rigid face plate provided with a plurality of apertures, pins inserted through the apertures and normally projecting above the face plate, and a backing layer of yieldable material bearing againstsaid pins, substantially as described.

7. In devices for correcting printing plates, the combination of a face plate provided With closely spaced apertures, pins inserted through said apertures and projecting above the face plate, and yieldablc means bearing against the opposite ends of said pins, substantially as described.

8. In devices for correcting printing plates, the combination of a face plate provided with closely spaced apertures, pins inserted through said apertures and projecting above the face plate, and a backing layer of yieldabl'e material bearing against the opposite ends of saidpins, substantially as described.

9. In devices for correcting printing plates, the combination of a face plate provided with closely spaced apertures, pins projecting through said apertures and be-' plates, the combination of a face plate provided with closely spaced apertures, pins slidably mounted through said apertures and, normally projecting above the face plate, said pins being provided with heads, and a-backing layer of yieldable material warms a bearing against said heads and .adapttfl to fiykonci said face plate End provided with yield iocaiiy to variations in pressure, sui'oeads on their rear ends, and a. relatively stantiaily as described. thick backing layer of rubber bearing.

11. In devices for correcting printing against said heads and held in space& re-

- plates. the combination of a. relatively thick latioii to the face plate by said heads, subandrigid face plate provfled with mperstantisriiy as &escribeoi. 1 tures, a piuraiity of pins projecting through saw. apertures and normally extenfing be- EMIL ERICKSSON. 

